1. Field of Invention
The invention relates to a navigation device. More specifically, the invention relates to a device which resets a guide route when a car (present position) has deviated from the guide route. The invention further relates to a device which is provided detailed road data by the operator. The invention further relates to a navigation device which makes it possible to easily set a destination.
2. Description of Related Art
In a conventional navigational device, a destination is set by a user and, then, a route to the destination is registered by manual operation, or the shortest route, the most suitable route or a recommended route to the destination is automatically found. The route to the destination is displayed as a guide route using a conspicuous line, such as thick line on a map picture, and the guidance is offered so that the car may move along the guide route. When the present position deviates from the guide route that is set at the time of departure, a new guide route is searched again starting from the present position.
Even when the car deviates from the guide route, however, the new guide route is not searched in case the present position is not included in the road data in the navigation device. That is, the guide route that was set at the time of departure is kept displayed or the guide route that was set at the time of departure is erased. Therefore, although there may exist another most suitable road to the destination in addition to the guide route that was set at the time of departure, the new most suitable road is not displayed as a new guide route. Besides, when the initially set guide route is erased, the driver quite loses his way to the destination. Moreover, when the start point of the newly searched route is located in a direction opposite to the direction of progress of the car, the driver must return to the start point.
The object of the invention, therefore, is to make it possible to search a guide route to a destination from a point on a guide road near the present position even when the present position does not exist on the guide road.
The navigation device is further equipped with a data storage medium (CD-ROM) storing road data covering over a predetermined range. Based upon the road data, a road map is displayed on the screen of the navigation device. This enables a moving body (car, other vehicle, such as a truck or bus, or any conveyance equipped with the invention), which will be called a car from here forward, to move favorably from the present position to the destination. The operator is furnished with various kinds of information, such as the name of a next intersection where the car should turn, the distance to the intersection, the direction of turn, etc.
The roads include those roads having street names in addition to national roads, such as Constitution Avenue, Washington Street, and Dachauer Street. According to the above-described navigation device, the operator is not informed of the name of a street into which he has entered when turning at the intersection.
When the name of the street has been widely known, therefore, it would be convenient if the operator is informed of the name of the street, like a signpost along the road indicating the name of the road. In such a case, the operator (driver) finds it better to learn the name of the street onto which he is going to proceed than to learn the name of the intersection where he should turn. In European countries and in the United States, in particular, every street has a name. Depending upon the guidance of the street names, therefore, it is possible to easily determine whether the direction in which the car is running is in agreement with the direction guided by the navigation device.
The object of the invention is as described below. That is, the street name of every road can be displayed on the picture, and the guidance route is displayed using the street name.
Using the navigation device, furthermore, the destination is set as described below. For instance, a mouse cursor is indicated on a map displayed on the screen of the navigation device. The cursor can be moved by the operator. The cursor is moved to any position on the map, and any point on the picture is specified as a destination. Alternatively, any building or facility is selected based upon the index data of telephone numbers and addresses in a list of various facilities stored in the CD-ROM, and the building or the facility is set as a destination.
When the destination is to be set using the conventional navigation device, as described above, the operator must be aware of the detailed address or the telephone number of the destination. When the operator is aware of neither the telephone number nor the detailed address of the destination, then, he must have the detailed map displayed to find the destination on the map. In this case, the map displayed on the navigation device may be scrolled to search for the destination.
The object of the invention is as described below. That is, the conditions for searching a desired destination are stepwisely changed, enabling the destination to be easily identified.